Having had, last night, a lively conversation over dinner with a woman who chid me (and sought to correct me) for insisting that sex is indeed binary, I think a clarifying post is in order.
Before I begin, I’ll pause to express surprise and dismay at how stubbornly fashionable, and how prevalent, denial of the fundamental dualism of sex has become, and remains; it’s a distressing symptom of the radical deconstruction and obliteration of all objective principles and categories that has grown, from small clouds of doubt at the beginning of the Enlightenment, to the ruinous tempest now smashing everything in the West to rubble. To insist, in these times, on the objective reality of the sex binary is to make oneself (as, for instance, J.K. Rowling has done) a heretic and a pariah. Nevertheless, there it is.
What is sex? Why does it exist? Why does it seem to be, in all species, a driving force whose urgency is second only to — if not primary to — the will to survive? Why does every human tradition always and everywhere, without exception, distinguish between male and female, not only as essential biological types or social categories, but as fundamental — and binary — divisions of transcendent metaphysical order?
The universal (until five minutes ago) human consciousness of the centrality of sexual duality, and its inclusion in the traditional systems of every culture, surely indicate something vitally important. I want to make this case as simply as possible, though, with the broadest possible appeal in this secular era, so I’m going to leave tradition and metaphysics out altogether — but not before I point out that duality and polarity are the very essence of sex; it is only the existence of the twin concepts of male and female that give the idea of sex any meaning at all. That said, though, we can imagine all sorts of binary concepts — hard and soft, black and white, awake and asleep, tall and short, loud and quiet, beautiful and ugly, friend and enemy, etc. — that are extremes of continua, and allow for the existence of intermediates. Biological sex, however, is not like that.
Why does biological sex exist at all? The answer: it exists, simply and unambiguously, as a mechanism of reproduction. It is how most multicellular organisms, and some unicellular organisms, reproduce. The mechanism involves the fusion of two sex cells, or gametes, each carrying half of the complete genome of the newly created organism (which before subsequent division is now a single, fertilized cell called a zygote).
In all multicellular organisms, with the exception of some yeasts and fungi, gametes come in two (exactly two) strikingly different forms. This is called anisogamy, and it is probably at least a billion years old. The male form is sperm; it is small (too small to see with the naked eye, and first observed by pioneering microscopist Anton van Leeuwenhoek in 1677), and it is motile. It has a tiny head, and a long whiplike tail that it uses to swim. The female form is the egg, or ovum; it is one of the largest human cells, and is large enough to see with the naked eye. It has a volume ten million times that of a sperm cell, and unlike the sperm, it is unable to move on its own.
These two kinds of sex cells — the two complementary components of human sexual reproduction — are all there is. There is no intermediate form, or mixture, or chimera, nothing halfway between a sperm and ovum. All human gametes are one or the other, and in biological terms, the combination of sperm and ovum to create new life is what sex is. There’s nothing cultural about any of it, and nothing that is a matter of opinion. As far as objective scientific facts go, this is as solid as it gets.
Those claiming that sex is nevertheless non-binary will now point to the indisputable existence of hermaphrodites, both human and animal. There are people with all sorts of ambiguous sexual characteristics, and there are animals that switch sexes during their lifespan, or even instantiate both sexes at once. Doesn’t that mean sex is a continuum?
No.
It’s important at this point to reiterate, and keep in mind, what sex is: a mechanism of reproduction involving the fusion of male and female gametes. The embryonic development, morphology, and life-cycle physiology of animal bodies can vary, and be disrupted, and make errors, in various ways, but the underlying mechanism of sex itself never changes at all.
Biologically, there are three forms of hermaphrodites — comprising two forms of “true” hermaphrodites, sequential and simultaneous, and what are called “pseudohermaphrodites”.
— Sequential hermaphrodites are animals that produce female gametes at one stage of life, and male gametes at another. Protogyny is when they start out as female and become male; the opposite is protandry. Some species go back and forth! (All three of these sequentially hermaphroditic forms can be found among reef-fish such as clownfish and wrasses; sometimes the changes appear to be induced by social-dominance hierarchies. The details are fascinating.)
— Simultaneous hermaphrodites are animals that can produce both male and female gametes at the same time. This is mostly found among snails and slugs, but there is one known vertebrate species — the mangrove killifish, Kryptolebias marmoratus — that pulls off this trick. Animals that can do this can do sexual reproduction all on their own.
— Pseudohermaphrodites produce only male or female gametes, but exhibit secondary morphological characteristics of the other sex. The example usually given is the female spotted hyena, which has what appears to be a penis, but is in fact an enlarged clitoris that functions as a birth canal.
Regarding humans: nearly every instance of “intersex” morphology is pseudohermaphroditic. Sequential hermaphroditism does not exist in any terrestrial vertebrate (and so not in humans), while simultaneous hermaphroditism — known formerly as “ovotestis” — is vanishingly rare; only 500 cases or so have ever been reported, and the bulk of those merely involve the presence of both male and female gonadic tissue, with actual production of both sperm and ova being even rarer (I haven’t yet been able to determine if any examples of it have ever been seen at all).
What should be clear after looking at all of this is that even the various forms of hermaphroditism — even having both ovaries and testes — provide no counterargument to the underlying duality of sex. They offer no examples of any sort of intermediate, hybrid components of the essential, binary mechanism of sex; they are merely various ways of producing one kind of gamete or the other (or both). This stubborn duality means that biological expression of the mechanism of sex only exists in four, clearly delimited forms:
1) The production of male gametes;
2) The production of female gametes;
3) The production of both;
4) The production of neither.
If sex were truly “non-binary”, there would be a vast continuum in between all of this, a vague and fuzzy biological domain in which sexually reproducing beings used something other than sperm (male) and ova (female) — some spectrum of gametes that are neither wholly one nor wholly the other — to create new life. But in the billion years of sexual life on Earth, such a thing has never existed, and it doesn’t exist now.
Sex is binary.
